Error while using ModRefiner standalone package

While i am running the program, it seems PDB file cannot be opened. Any suggestions to resolve this?
Also i don't have any reference protein, so will there be problem while using the same protein as reference?

$ ./mcrefinement Desktop/ModRefiner Desktop/ModRefiner c_mutant.pdb c_mutant.pdb 0
PDB file can not be opened Desktop/ModRefiner/c_mutant.pdb